1. Field of the Invention
The present invention relates to a stereoscopic endoscope system which includes a stereoscopic endoscope having a right image pickup section and a left image pickup section.
2. Description of the Related Art
A general endoscope apparatus is a so-called 2D endoscope apparatus for observing a subject site as a planar image. However, since the planar image does not give a perspective feeling, a stereoscopic effect cannot be obtained when subtle unevenness or the like on a surface of a body cavity wall is observed as a specific example of the subject site.
Therefore, a stereoscopic endoscope apparatus making it possible to three-dimensionally observe an object has been proposed. A conventional stereoscopic endoscope apparatus is adapted to, for example, form object images with two objective optical systems having a parallax which are provided at a distal end portion, transmit the object images to an eyepiece portion at a rear end portion via a pair of relay optical systems and a pair of eyepiece optical systems, and perform megascopic observation or image pickup by a pair of TV cameras.
As an example of such a conventional stereoscopic endoscope apparatus, for example, a second embodiment of Japanese Patent Application Laid-Open Publication No. 2004-222937 describes a stereoscopic endoscope apparatus which is provided with a right image-forming optical system, a right CCD, an ID memory for outputting a right identification signal, a left image-forming optical system, a left CCD, an ID memory for outputting a left identification signal, and a rearrangement apparatus to which right and left video signals and identification signals are inputted, wherein the rearrangement apparatus outputs a right video signal and a left video signal to odd and even lines of a display device, respectively, based on the identification signals. Here, the display device is such that polarizing plates with polarization directions different from each other by 90 degrees are attached on the odd lines and the even lines, respectively. Therefore, it is possible to three-dimensionally observe an image by observing the display device via a pair of polarizing glasses having a right lens in a polarization direction capable of causing video transmitted through the odd lines to be transmitted and a left lens in a polarization direction capable of causing video transmitted through the even lines to be transmitted. Further, a first embodiment of the official gazette describes a technique in which right video signals and left video signals are sequentially displayed to be stereoscopically observed via a pair of liquid crystal shutter glasses.
Further, Japanese Patent Application Laid-Open Publication No. 10-126814 describes a technique in which a field judging circuit for judging whether each field is for a right eye or for a left eye, and an adding circuit for adding a predetermined display signal to a recording portion in at least one of a judged right eye field and a judged left eye field are provided.
Further, Japanese Patent Application Laid-Open Publication No. 2005-223495 describes a technique in which three-dimensional video displaying means provided with a display surface on which left eye pixels and right eye pixels are alternately arrayed and a parallax barrier which arrays light transmitting areas and light shielding areas alternately according to the array of the right/left eye pixels to generate a parallax, and viewing position confirmation information displaying means for displaying viewing position confirmation information for a left eye and viewing position confirmation information for a right eye within a left half of the display surface and within a right half of the display surface, respectively, are provided so that an observer can determine an appropriate viewing position based on the viewing position confirmation information at time of viewing video.
The technique described in each of the official gazettes described above is a technique utilized at time of using a manufactured stereoscopic endoscope. A point which occurs at time of manufacturing the stereoscopic endoscope will be described with reference to FIGS. 32 to 35.
First, FIG. 32 is a block diagram showing a configuration in which a stereoscopic endoscope in which right and left image pickup sections and right and left memories are reversely connected is observed on a 3D monitor.
A stereoscopic endoscope 101 is provided with: an R image pickup section 112r and an R output section 115r which are arranged on a right side of an endoscope body 111; an L image pickup section 112l and an L output section 115l which are arranged on a left side of the endoscope body 111; an R signal line 113r extended from the R image pickup section 112r; an L signal line 113l extended from the L image pickup section 112l; an R memory 114r which stores R correction information for correcting a right eye image, and an L memory 114l which stores L correction information for correcting a left eye image.
The R image pickup section 112r and the L image pickup section 112l are accurately positioned and assembled so that a right eye image and a left eye image for constituting a stereoscopic image can be acquired, respectively. However, positioning at a pixel pitch level is difficult. Therefore, correction information for cutting out a right eye image acquired from the R image pickup section 112r and a left eye image acquired from the L image pickup section 112l and performing positioning so that a stereoscopic image can be accurately configured is recorded in each of the R memory 114r and the L memory 114l. 
A 3D monitor 105 is adapted so that an image outputted from the R output section 115r of the stereoscopic endoscope and an image outputted from the L output section 115l of the stereoscopic endoscope are inputted as a right eye image and a left eye image, respectively, to display a stereoscopic image.
It is assumed that, in such a configuration, the R signal line 113r extended from the R image pickup section 112r is connected to the L memory 114l, and the L signal line 113l extended from the L image pickup section 112l is connected to the R memory 114r due to an assembly mistake.
In this case, a right eye image corrected with L correction information is outputted from the L output section 115l and displayed on the 3D monitor 105 as a left eye image, and a left eye image corrected with R correction information is outputted from the R output section 115r and displayed on the 3D monitor 105 as a right eye image.
Therefore, an inspection using a 2D monitor 103, as shown in FIG. 33, is performed at time of assembly. FIG. 33 is a block diagram showing a configuration in which a manufacturing inspection of the stereoscopic endoscope shown in FIG. 32 is performed with use of a 2D monitor.
The 2D monitor 103 is used by being connected to one of the output sections of the stereoscopic endoscope 101. In the example shown in FIG. 33, the 2D monitor 103 is connected to the L output section 115l. 
Then, for example, a finger is inserted in an image pickup range of only the L image pickup section 112l to confirm whether the finger is displayed on the 2D monitor 103. In an incorrect connection state as shown in FIG. 33, since it is a right eye image picked up by the R image pickup section 112r that is outputted from the L output section 115l, the finger is not observed on the 2D monitor 103, and it can be detected that the L image pickup section 112l is not connected to the L output section 115l. Therefore, it is possible to confirm the connection state of the R signal line 113r and the L signal line 113l again and return the connection state to a correct connection state.
Next, an example in which detection is not possible only by such an inspection method will be described with reference to FIGS. 34 and 35. FIG. 34 is a block diagram showing a configuration in which a stereoscopic endoscope in which pieces of correction information to be stored into memories are stored with left and right reversed is observed on a 3D monitor; and FIG. 35 is a block diagram showing a configuration in which a manufacturing inspection of the stereoscopic endoscope shown in FIG. 34 is performed with use of a 2D monitor.
A right eye image should be corrected with R correction information, and a left eye image should be corrected with L correction information. However, in the example shown in FIGS. 34 and 35, the R correction information and the L correction information are reversely stored in the memories. Therefore, the R image pickup section 112r is connected to the L memory 114l and the R output section 115r, and the L image pickup section 112l is connected to the R memory 114r and the L output section 115l. 
At this time, when the 2D monitor 103 is connected to the L output section 115l, and a finger is inserted in the image pickup range of only the L image pickup section 112l, the finger is displayed on the 2D monitor 103, and the connection state of the image pickup sections appears to be correct at a glance. It is difficult to confirm whether a displayed left eye image has been correctly corrected with L correction information or incorrectly corrected with R correction information, by observing only the 2D monitor 103.
Therefore, it is also conceivable to actually observe and confirm a stereoscopic image further using a 3D monitor, as shown in FIG. 34. It is known, however, that an ability to recognize a stereoscopic image varies among individuals. Some literatures describe that about 10% of people cannot recognize a stereoscopic image as 3D. Therefore, even if a stereoscopic image is displayed with use of a 3D monitor to perform an inspection for confirming whether correction information is correct or incorrect by visual inspection, a correct inspection result cannot be necessarily obtained.